The invention concerns a rotary piston machine with a housing and a piston, which piston is rotatably arranged in a hollow space of the housing and is rotatably fixedly connected with a shaft passing through the housing, with at least one inlet channel and one outlet channel being provided in the housing for the delivery and exhaust of a working fluid to and from the hollow space.
The invention has as its object the provision of a rotary piston machine of the above-mentioned kind which is of simple construction and in which the inlet and outlet openings for the working fluid can be controlled in a simple way.
This object is solved in accordance with the invention in that the hollow space has a section in the form of a cylindrical annular space co-axial to the shaft, that the piston is formed as a annular piston in the shape of a cylindrical tube section which is received in the annular space of the housing and is guided for axially shifting movement in the annular space of the housing, and in that the end surfaces of the annular space and of the annular piston which face one another are formed as continuous wave surfaces with amplitudes directed parallel to the machine axis, so that the inlet and outlet openings lie inside of an axial region of the lateral annular space surface, which region is defined by the maximum axial spacing of the wave hollows of the end surfaces facing one another.
The rotary piston machine according the invention can be driven as a pump or, in so far as the wave surfaces of the annular space and of the ring piston are formed with at least two wave crests and wave hollows over 360xc2x0 of the circumference, also as a motor. In general the machine is so formed that the housing remains stationary and the piston rotates with the shaft. In principle, however, it is possible to also use the opposite arrangement, in which the housing rotates relative to the non-rotating piston. However, in this case the connections for the delivery and the exhaust of the working fluids become complicated. The piston can be axially slidably supported on the shaft or can be rigidly connected with the shaft, in which case the shaft is axially slidably supported in the housing.
In the inventive solution, the working space of the rotary piston machine forms variable hollow spaces between the end surfaces of the annular space and of the annular piston which slide on one another. Each hollow space expands or diminishes in size during the rotation and the axial oscillating movement of the piston relative to the housing. The inlet opening and outlet opening can be so arranged in the radially outer or radially inner lateral boundary surfaces of the annular space that they are cyclically opened and again closed by the piston wall, in order in the case of a pump for example to suck in a working fluid and again expel it, or in the case of a motor to suck in a fuel mixture, to compress the mixture and subsequently to exhaust the combustion gases.
Since the annular piston is formed rotationally symmetrical with respect to its rotation axis, a completely smooth running of the piston is obtained. The same applies also in the case of a rotational housing. No essential sealing problems appear. Movable valves for the opening and closing of the inlet and outlet openings are not required.
Preferably the inlet opening and the outlet opening are so arranged that in the circumferential direction one of the openings lies in front of and the other lies behind a wave crest of the end surface of the annular space. In this construction of the rotary piston machine as a motor, on a circumference of 360xc2x0 one inlet opening and one outlet opening are provided. In the construction of the rotary piston machine as a pump preferably two inlet openings and two outlet openings are provided for each end surface of the piston.
One of the end surfaces can be formed so as to have an at least nearly sinusoidal shape. The other end surface is preferably so designed that an axial movement of the piston of maximum uniformity is achieved during one revolution and no jerking or extreme acceleration of the piston in the axial direction appears.
In a first embodiment of the invention the piston is biased in the axial direction, for example by a spring, so that its end surface constantly lies on the end surface of the associated annular space. The force by which the surfaces are pressed together can also be regulated by the pressure fluid in the annular space.
In another embodiment, in a lateral surface of the piston or of the annular space a groove is formed in which is received a guide element connected to the other part (annular groove, piston), so that the path of the groove in the circumferential direction corresponds to the wave shape of the end surface of the annular space. Thereby the translational movement of the piston and of the cylinder relative to one another is controlled by the groove. The end surfaces of the piston and the annular space need not contact one another, so that wear of these surfaces by sliding on one another is avoided.
Another solution, for reducing the wear of the end surfaces by sliding friction exists in that in one of the end surfaces of the annular space and piston facing one another, at least one guide element is rotatably supported for rolling on the other end surface.
In a further embodiment of the invention, two annular space/annular piston arrangements of the previously described kind are arranged coaxial to one another so that the two pistons arranged on the same shaft move in common between the end surfaces of the two annular spaces.
For example, the two pistons can be unified into a one piece double piston. In this case the two end surfaces of the hollow space or of the two joined together hollow spaces are so arranged relative to one another that the maximums and minimums of their wave surfaces lie on the same generatrix of the cylindrical lateral surface of the hollow space. Thereby it can be assured that the two end surfaces of the rotating annular piston constantly slide uniformly on the two end surfaces of the hollow space when the piston rotates.